12Vdc motor control


Thread Starter


I would like to control a 12Vdc motor from a microprocessor. The motor draws about 4A. What should I use to interface between the motor and the microprocessor?

Robert Scott

The simplest interface would be an N-channel logic level power MOSFET that sinks motor current to ground and whose gate is driven directly by a CMOS logic level output. Make sure to parallel the motor with a diode so that when you turn off the motor the inductance of the motor won't cause a turn-off spike that blows the MOSFET. Don't bother with a heat sink. The MOSFET will run cool unless you try to switch it on and off at a high frequency.

Roberts Scott
Real-Time Specialties
Embedded Systems Consulting

Hyun-Soo Song

I don't know about your target plant.
Therefore you must build a Inverter.

I think there are 3 methods for your solving:

First, to use of specific module chip for DC motor.

Second, to use of high-current transistor + fast response diode.

Third, to use of Low voltage MOS-FET with Gate-amp.

I think the first method is best.

Many Semiconductor Company produce these specific module chip.

For example, like L298 (can't apply at your application of its current limitation) chip is very powerful, and simple.

So you need to find out newer chip.

Usually the Datasheet gives you standard circuit.

The econd and third method give you free design level of circuit.

The MOS-FET needs the Gate-amp but needs less losses.

Texas Instrument's IR21xx series are good solution for Gate amp.

So the rudiments like you, the second method is better.

You must study the H-Bridge type of Inverter topology and a use of free-wheeling diodes.

Good Luck!

[email protected]
You can use a HDD-1V20 or HDD-1V40 from Power-io.com This is a DC switching, mosfet based, solid state relay.

Set-up the microprocessor as either on/off or as a PWM output up to 15KHz.

[email protected]
Hi u,

i and u have the same interested thing, i see that control dc motor is lot of useful practice! so i try to find the method that is simple and resultant!! at final i also find out that there are two main method to make that work, those are linear control and PWM (pulse width modulation!). i think u can read and download them on the internet...!!

good luck to u!! dont forget send mail for me if u success!!